The commonplace, seemingly straightforward, task of administering an injection of medication with a syringe is often more complicated than it first appears. With syringes in common use by clinicians today, when a certain amount of medication is to be taken from a bottle (vial), the clinician inserts the syringe needle into the bottle, brings the bottle up to eye level, aspirates or withdraws slightly more than the required amount of medication from the bottle into the syringe, and then gradually injects a portion of the medication from the syringe back into the bottle until the desired amount of medication is contained in the syringe. Often, as the user tries to gradually empty the syringe contents back into the bottle, more medication than intended is inadvertently returned to the bottle. As a result, the clinician must either inject less medication than desired, or repeat the process again. If the clinician cannot bring the bottle to eye level (as when aspirating from a large or hanging container), the process is much more difficult and inaccurate, because of different angle of vision.
When the clinician wishes to inject only a portion of the medication contained in the syringe, the process is even more complicated. To be more accurate the clinician should bend forward and look at the plunger level to make sure how much has been injected. If more than intended has been injected, there is no way to bring it back—a particularly dangerous situation when injecting more critical medications.
There are some occasions where an expensive medication like botulinum toxin, or a critical and potentially dangerous medication like lidocaine, should be injected with multiple, repeated, injections. With conventional syringes, there is no way one person can do so accurately. Many times, injection should be done while looking at monitor; so it is not possible to look at the syringe at the same time. Furthermore it is extremely difficult to inject a specific amount to one point. (See, e.g., P. Shenot and J. Mark, Intradetrusor onabotulinumtoxinA injection: how I do it, The Canadian Journal of Urology, 20(1), 6649 (February 2013)). This means that, most of the time, there should be another person to help with starting and stopping injections at specific volumes. Still it is common that, in any spots more than needed amount of Botox is injected and at the end there is nothing left for other areas. This practice is neither effective nor efficient. Accordingly, there is a need for new syringe designs that aid the clinician in more efficiently and effectively carrying out these procedures.